Now on my bigger craftsman with the hi low rearend with a 5 bolt hub. Would I need to have the rearend posi locked in order to put 2 tracks on the back? I have seen atv's with a track on each wheel so does that mean they had to be locked out in posi 4wd?

I would say anything is possible, I think locking it into posi would be needed or it might cause it to drift to one side or the other, Are you wanting to make a snow mobile out of a mower? or build a tank for off roading?

I would add i dont think this would be a cheap build. unless you have the parts available....?